Neutral and Cationic Palladium Complexes of P ‐Stereogenic Phosphanes Bearing a Heterocyclic Substituent

The coordination chemistry of 13 optically pure P ‐stereogenic diarylmonophosphanes P(Het)PhR [Het = 4‐dibenzofuranyl (DBF), 4‐dibenzothiophenyl (DBT), 4‐dibenzothiophenyl S , S ‐dioxide (DBTO 2 ) and 1‐thianthrenyl (TA); R = OMe, Me, i Pr, Fc (ferrocenyl)] to Pd‐allyl moieties is described. Both neutral [PdCl(η 3 ‐(2‐methylallyl)(κ P ‐ P )] and cationic [Pd{η 3 ‐(2‐methylallyl)(κ P ‐ P ) 2 }]PF 6 complexes have been prepared. Coordination of the heteroatom of the heterocycle was only possible in the case of TA‐based phosphanes; these furnished complexes of the type [Pd{η 3 ‐(2‐methylallyl)(κ 2 P,S ‐ P )}]PF 6 after chloride abstraction with TlPF 6 . The crystal structure of the complex [Pd(η 3 ‐2‐methylallyl)(κ 2 P,S ‐PPh(OMe)(1‐TA)]PF 6 is reported. The neutral Pd complexes were found to be highly active in the hydrovinylation of styrene after activation with AgBF 4 , except for the TA‐based phosphanes. The cationic Pd complexes were evaluated in allylic alkylation and amination with the model substrate rac ‐ trans ‐1,3‐diphenylprop‐2‐enyl acetate ( rac ‐ I ), achieving total conversions and up to 70 % ee .